What are the diagnostic tests and procedures for kidney cancer?

Diagnostic Tests and Procedures for Kidney Cancer

The primary diagnostic approach for kidney cancer involves imaging studies, particularly contrast-enhanced CT scans of the chest, abdomen, and pelvis, which are mandatory for accurate staging of renal cell carcinoma. 1, 2

Initial Detection and Evaluation

• More than 50% of renal cell carcinomas are detected incidentally through abdominal imaging such as ultrasonography, CT scans, or MRI 1
• Diagnosis is typically first suggested by ultrasonography and then confirmed by CT scan, which allows assessment of local invasiveness, lymph node involvement, and distant metastases 1, 2
• High-quality abdominal cross-sectional imaging is essential to characterize and clinically stage renal masses 2
• MRI provides additional information about local advancement and venous involvement by tumor thrombus, particularly useful when intravenous contrast cannot be used 1

Laboratory Tests

• Laboratory evaluation should include: 1, 2

  • Serum creatinine
  • Hemoglobin
  • Leukocyte and platelet counts
  • Lymphocyte-to-neutrophil ratio
  • Lactate dehydrogenase (LDH)
  • C-reactive protein (CRP)
  • Serum-corrected calcium

• These laboratory values serve both diagnostic and prognostic purposes, with some being used for risk assessment within different prognostic scoring systems 1

Imaging Protocol

• Contrast-enhanced CT scan of the chest, abdomen, and pelvis is the gold standard for diagnosis and staging 1, 2
• Triple-phase CT scanning is particularly valuable for characterizing renal masses 3
• For patients with contrast allergies or renal insufficiency, a high-resolution non-contrast CT scan of the chest combined with abdominal MRI is recommended 1
• Bone scans or brain CT/MRI are not recommended for routine practice unless specifically indicated by clinical or laboratory findings 1
• FDG-PET is not a standard investigation for diagnosis and staging of clear cell RCC and should not be used 1

Renal Mass Biopsy

• A renal tumor core biopsy provides histopathological confirmation of malignancy with high sensitivity and specificity 1
• Biopsy is especially recommended in two scenarios: 1
  • Before treatment with ablative therapies
  • In patients with metastatic disease before starting systemic treatment
• Complications from biopsy such as bleeding or tumor seeding are rare or even exceptional 1
• The final histopathological diagnosis, classification, grading, and evaluation of prognostic factors are based on the nephrectomy specimen when available 1

Histopathological Classification

• Clear cell RCC is the most frequent subtype (70-85% of cases) 1, 2
• Other subtypes include: 1
  • Papillary RCC (7-15%)
  • Chromophobe RCC (5-10%)
  • Collecting duct carcinoma (rare)
• Each subtype has distinct genetic and molecular characteristics that may guide treatment decisions 1

Special Considerations

• Genetic counseling should be considered for patients ≤46 years of age, those with multifocal or bilateral renal masses, or if personal/family history suggests a familial renal neoplastic syndrome 2
• Approximately 2-3% of RCCs are hereditary, with von Hippel-Lindau disease being the most common syndrome 1
• Patients with end-stage renal disease, on dialysis, or with renal transplants have an increased risk of RCC 1

Common Pitfalls and Caveats

• Relying solely on ultrasonography for definitive diagnosis may miss small lesions or fail to properly characterize them 1
• Not performing a biopsy before ablative therapy or systemic treatment can lead to inappropriate management 1
• Neglecting to evaluate the chest for potential metastases can result in understaging 1
• Failing to consider hereditary syndromes in younger patients or those with bilateral/multifocal lesions may miss important genetic diagnoses 2